1. Field of the Invention
The present invention relates to a valve accessory, and in particular to an adaptor for a valve actuator.
2. Summary of the Prior Art
Valves, particularly industrial valves, are usually opened and closed by valve actuators. Typically, a valve has a rotational control stem which opens the valve mechanism when it is rotated one way and closes the valve when rotated the other. By convention, the direction of opening is usually anticlockwise looking along the control stem towards the valve mechanism.
Rotation of the control stem is carried out by the actuator, usually in response to a control signal. The actuator has a rotational drive and this engages with the control stem to rotate the control stem. The actuator housing is usually attached to the valve itself, at a part other than the control stem, in order more efficiently to generate torque to rotate the control stem with respect to the rest of the valve.
The present invention is particularly concerned with part turn actuators in which the rotational drive of the actuator has a limit of rotation of less than a complete revolution, i.e. less that 360xc2x0.
For satisfactory operation and to minimise leakage, valves are manufactured with small dimensional tolerances. This has led to some of their dimensions being standardized. This is the case in terms of the dimensions of the interface between a valve and a part turn actuator. The relevant standards are ISO 5211 (reference number ISO 5211:2001 (E), published Feb. 15, 2001) and DIN 3337 (published September 1985). The contents of these publications are incorporated herein by reference. Where relevant in this specification, they will be referred to together as ISO 5211/DIN 3337, or separately, as appropriate. Devices which are described as non-ISO 5211/DIN 3337 are devices which do not conform either to ISO 5211 or to DIN 3337.
To be directly attachable to a valve of standard dimensions, an actuator must also have standard dimensions. An advantage of the standardized valve/actuator assembly is that a bracket and coupling usually need not be used since the actuator can be directly mounted onto the valve. Of course, manufacture of an entire actuator in accordance with international standardized dimensions places restrictions on the actuator. Furthermore, for an existing actuator design standardisation often requires extensive redesign of the whole actuator which is expensive. Still further, the adoption of such standards can make existing, otherwise satisfactory actuators and actuator designs obsolete.
In a general aspect, the present invention provides an adaptor for mounting a non-ISO 5211/DIN 3337 actuator to an ISO 5211/DIN 3337 valve.
Preferably, in a first aspect, the present invention provides a valve actuator adaptor having a body with first and second mounting surfaces, the adaptor having an aperture extending through the body, the aperture being open at each mounting surface, the first mounting surface having valve attachment points arranged around its aperture in accordance with ISO 5211/DIN 3337, the second mounting surface having valve actuator attachment points not in accordance with ISO 5211/DIN 3337, and a coupling link locatable in the aperture, a first end of the coupling link having a first surface shaped for engagement with a valve rotational control means and a second end of the coupling link having a second surface shaped for engagement with an actuator rotational drive means, the coupling link being rotatable within the aperture;
wherein the valve attachment points of first mounting surface comprise holes extending from said first mounting surface to an exposed third surface intermediate along the axial length of the adaptor, the holes being arranged to receive screws or bolts for securing the adapter to the valve, the third surface having recesses therein around said holes, the walls of the recesses being shaped to prevent rotation of the head of said screws or bolts or nuts mounted on said bolts.
Preferably, in a second aspect, the present invention provides a method of assembling a valve arrangement including the step of mounting a non-ISO 5211/DIN 3337 actuator in relation to ISO 5211/DIN 3337 valve by attachment of an adaptor between the valve and the actuator.
Preferably, in a third aspect, the present invention provides a method of modifying a valve arrangement, wherein the valve arrangement includes an ISO 5211/DIN 3337 valve which is operable via an actuator, the method including the step of mounting a non-ISO 5211/DIN 3337 actuator in relation to the valve by attachment of an adaptor between the valve and the actuator.
In another general aspect, the present invention provides the assembly comprising a valve actuator adaptor having a mounting surface with valve attachment points arranged in accordance with ISO 5211/DIN 3337, with an actuator and a valve mounted thereon.
The valve actuator attachment points are arranged around the aperture opening on the second mounting surface not in accordance with 150 5211/DIN 3337.
Preferably, the valve attachment points are valve attachment holes formed in the body of the adaptor, each valve attachment hole opening at the first mounting surface. The actuator attachment points are preferably arranged around the aperture opening at the second mounting surface. Preferably the actuator attachment points are actuator attachment holes formed in the body of the adaptor, each opening at the second mounting surface. More preferably, one of the valve attachment holes is offset from any of the actuator attachment holes. This in the sense that the principal axis of the valve attachment hole does not coincide with the principal axis of any of the actuator holes (although these axes may be parallel). Even more preferably, all of the valve attachment holes are offset from all of the actuator attachment holes. Stated in an alternative way, preferably none of the valve attachment holes is in line with any of the actuator attachment holes.
This arrangement may allow the depth of one or more of the valve attachment holes to overlap with the depth of one or more of the actuator attachment holes but wherein none of the holes, preferably, is continuous with another. Therefore, for a given hole depth, the axial length of the body of the adaptor can be shorter than if the holes were in line. This is particularly the case where each hole is open only at one end. In that case, the holes may be tapped to engage with a screw thread of an attachment screw or bolt.
One function of the adaptor is usually to allow torque to be transmitted from the actuator to the valve. Reduction in the axial length of the adaptor (as discussed above) can give rise to more efficient transmission of torque from the actuator to the valve. Typically, therefore, the actuator includes a torque transmission coupling, which is discussed is more detail below. It is usually undesirable to transmit relatively high torques over long axial torque transmission couplings since the longer the transmission coupling, the more elastic xe2x80x9ctwistxe2x80x9d it has.
In the case where one or more of the valve or actuator attachment holes is open at both ends (for example, open at both the first mounting surface and at the second mounting surface) then the overlap (referred to above) of one hole with another can be total. As an example, for attachment of the adaptor to a valve, attachment means such as a screw, bolt or similar may be passed along the length of the valve attachment hole to the valve and tightened from the end of the hole which is not adjacent the valve, i.e. from the second mounting surface end. As will be clearly understood, another example could be of attachment of the adaptor to an actuator via an actuator attachment hole.
The valve attachment holes may be radially offset from the actuator attachment holes. Additionally or alternatively, they may be circumferentially offset from each other. Use of the words xe2x80x9cradialxe2x80x9d and xe2x80x9ccircumferentialxe2x80x9d imply that the adaptor has substantially circular, or at least rounded cross section, and this is preferred, but it is not essential. The adaptor could have a square, hexagonal or other polygonal cross section, for example.
With respect to the actuator attachment holes, these are preferably counterbored and preferably extend through the axial length of the body. Typically there are two actuator attachment holes, located on radially opposite sides of the body.
On the second mounting surface, there may also be located an actuator locating peg or recess, preferably a peg. This is preferably a dowel peg formed integrally with the body during, for example, die casting of the body. The location peg allows easy location of the adaptor with respect to the actuator prior to attaching the two together.
Preferably there are two (or more) locating pegs on the second mounting surface. These are typically located approximately equispaced from each other and/or the actuator attachment holes.
The actuator attachment holes may be tapped with a screw thread. However, preferably they are not, reducing the need for machining after die casting the body. This implies that attachment using the holes is via a nut and bolt arrangement, or that the valve/actuator has a tapped hole for a screw thread. The same applies to the valve attachment holes.
Preferably, a valve attachment hole extends from the first mounting surface to an outer recess formed on the body, rather than extending to the second mounting surface. This arrangement means that the adaptor may be fitted first to the actuator (by attachment through the actuator attachment holes) and then the adaptor may be connected to the valve by attachment through the valve attachment holes, by attachment means (such as a screw or bolt, etc.). The attachment means is then capable of being accessed for tightening via the outer recess in the body. In the case of a screw, the head of the screw is accessible for tightening even when the adaptor is in place between the actuator and the valve.
In a particularly preferred formation, the outer recess may be shaped so that the valve attachment hole extends through a partial flange in the body.
In use, the mode of connection of the adaptor to the valve depends to some extent on the shape of the valve. The features described are of course applicable to all aspects of the invention. In this regard xe2x80x9cvalvexe2x80x9d is to be understood as the device, including a valve housing, in which a valve mechanism is located. In fact, the adaptor is normally attachable to a part of the valve housing. The shape of the part of the valve housing to which the adaptor is to be attached is often determined to some extent by standardization (i.e. in the present case by ISO 5211/DIN 3337). Usually, it will be in the form of a neck, open at one end, with a mounting surface shaped with attachment holes in accordance with ISO 5211/DIN 3337.
The neck may have a flange, the mounting surface being the surface of the flange. In that case, the adaptor may be attached to the flange via a bolt and nut, the arrangement being capable of being tightened from behind the flange and/or from the recess on the adaptor.
In the case where the neck of the valve does not have a flange, attachment holes may be formed extending into the neck itself, parallel to the neck axis. In that case, the attachment holes in the neck will usually be tapped to accommodate a screw (for example, a socket head cap screw) attaching the adaptor to the valve.
The ISO 5211/DIN 3337 standardization covers many different valve neck sizes and shapes. To improve the versatility of a particular adaptor according to the present invention, there may be provided one or more releasably attachable body extensions whereby one particular adaptor is attachable to more than one size or shape of valve neck. This constitutes a further, preferred feature of the first aspect of the invention.
Preferably, each releasably attachable body extension is clickwise engageable with the body of the adaptor. Preferably, such a body extension is locatable on the body at one of the body recesses described above. In place, the body extension extends radially from the body to provide a valve attachment point, preferably a valve attachment hole. In this way, an arrangement of body extensions can provide a series of valve attachment holes for the adaptor at a desired radial distance from the axis of the body. This radial distance is adjustable by using a set of body extensions of different size, and hence adjusting the location of the extended valve attachment holes. When located in place, the body extensions form a partial extended flange around the body, a surface of this partial flange located adjacent the first surface. Preferably, the extended valve attachment holes are located radially outwards but radially in line with the valve attachment holes found in the body.
Preferably, the body extensions described are moulded from plastics material.
The adaptor in use may allow an actuator to be fitted to an ISO 5211/DIN 3337 valve. It is noted that the actuator should generate torque (with respect to a valve housing). Valves of interest usually have rotational control means to open and close the valve mechanism. This is usually in the form of a valve rotational control stem which extends along the valve neck. The actuator has rotational drive means which, when the actuator is operated, rotates to rotate the rotational control means. Typically, the rotational drive means is shaped to engage with the rotational control means. In use, one or both of the rotational drive means and the rotational control means may be located in the aperture formed in the adaptor body, the adaptor serving as a sleeve around them.
However, there can be a problem either when the rotational drive means and the rotational control means are not correspondingly shaped to engage with each other, or when they do not reach far enough along the axis of the adaptor to engage with each other. In such case, the adaptor may provide a coupling link which is shaped to engage with a rotational drive means and with a rotational control means. This constitutes another general, independent aspect of the invention. In this aspect of the invention, it is not essential (although it may be preferable) that the adaptor is shaped and sized to fit to an ISO 5211/DIN 3337 valve.
The coupling link first surface may be the surface of a projection from the coupling link (a xe2x80x9cmalexe2x80x9d connector, suitable for engagement with a xe2x80x9cfemalexe2x80x9d connector formed on the rotational control means). Preferably, the coupling link first surface is the surface of a recess formed in the coupling link (a xe2x80x9cfemalexe2x80x9d connector). Similarly, the coupling link second surface may be a male connector but is preferably a female connector. Accordingly, the fifth aspect of the invention is preferably directed towards the coupling of a xe2x80x9cmalexe2x80x9d actuator rotational drive means with a xe2x80x9cmalexe2x80x9d valve rotational control means. Similarly, any of the other aspects of the invention are preferably directed towards the coupling of a male actuator rotational drive means with a male valve rotational control means.
Preferably, the coupling link is a hollow or partially hollow cylinder, the internal surface of the cylinder incorporating the first and second surfaces.
Suitable shapes for the valve rotational control means and/or the actuator rotational drive means are known in the art, for example parallel square, diagonal square, flat head or keyway. It is to be understood that the invention is applicable to all of these shapes.
The coupling link may be separable into two parts, each having a section which is correspondingly shaped which are engageable together by engagement of the correspondingly shaped sections. In that case, the first and second surfaces typically are each located on a different part.
The corresponding shape of the sections of the two separable parts is preferably polygonal in cross section. The shape may, for example, be triangular, rectangular, square, hexagonal. It may also be star-shaped, for example. If star shaped, preferably the star has 8 points or more Even more preferably, the corresponding shape may be serrated (i.e. a many-pointed star). Most preferably, the shape is finely serrated, for example with 20 or more, 36 or more or 48 or more serrations.
Typically, one of the parts is an insert being insertable into the other part for engagement. In that case, the insert has an outer surface which is correspondingly shaped for engagement with a correspondingly shaped opening in the other part.
Typically, one of the separable parts is replaceable by another. In this way, a coupling link may be provided which, on changing one of the parts, is shaped for engagement with a different rotational drive or control means.
Preferably, the replaceable part of the coupling link is an insert, preferably with a serrated outer surface, the internal surface of the insert preferably being the first surface of the coupling link. That is, it is preferably the insert which engages with the valve rotational control means.
The use of serrations has various advantages over shapes with fewer edges. Firstly, the serrations provide good use of radial space for a given torque transmission. Secondly, the serrations provide lower backlash because of larger diameter of connecting surface. Thirdly, the serrations provide lower local stress because the torque is resisted by a larger number of positions. Furthermore, the insert can be positioned in many different orientations with respect to the remainder of the coupling to suit applications and makes it unnecessary to be precise in the orientation of the insert. Still further, the preferred feature allows easier production of the inserts because of only a small amount having to be removed per tooth.
In another aspect, the present invention provides a valve actuator adaptor according to the fourth aspect or the fifth aspect, with any of the features (including preferred features) described with respect to the fifth aspect or the fourth aspect, respectively.
In a further aspect, the present invention provides a valve actuator arrangement including an adaptor according to either the fourth or the fifth aspect and a non-ISO 5211/DIN 3337 actuator, the adaptor being attachable to the actuator at the second mounting surface of the adaptor.
In another aspect, the present invention provides a valve arrangement including an adaptor according to either the fourth or the fifth aspect and an ISO 5211/DIN 3337 valve, the adaptor being attachable to the valve at the first mounting surface of the adaptor.